Abacus



FIG. 1 is a front elevation view of the abacus showing my new design;

FIG. 2 is a back elevation view thereof;

FIG. 3 is a left elevation view thereof;

FIG. 4 is a right elevation view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is another perspective view thereof.

CLAIM The ornamental design for an abacus, as shown and described.